Project title:
Temporal changes of intrinsic frequency during episodes of myocardial ischemia and myocardial infarction 

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Grant information:
AHA

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Relevant publications:

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Project Description:

This project analyzes cardiovascular dynamics using the Intrinsic Frequency (IF) method in a standard occlusion/reperfusion rat model. A total of 45 rats were used, with data collected at six different time points corresponding to various stages before and after occlusion and reperfusion.

The six time points are as follows:

- Point 1: 5 minutes before occlusion (labeled as -5)  
- Point 2: 2 hours after reperfusion (labeled as 150)  
- Point 3: 5 minutes after occlusion (labeled as 5)  
- Point 4: 5 minutes before reperfusion (labeled as 25)  
- Point 5: 15 minutes after occlusion (labeled as 15)  
- Point 6: 5 minutes after reperfusion (labeled as 35)

At each of these time points, we extracted a set of Intrinsic Frequency (IF) metrics from the pressure waveform data. These metrics include:

Parameter              Description
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omega1_bpm        First intrinsic frequency (beats per minute)
omega2_bpm        Second intrinsic frequency (beats per minute)
Del-omega            Difference between omega1 and omega2
phi1                       Initial phase of first intrinsic frequency
phi2                       Initial phase of second intrinsic frequency
RHDN                    Relative height of decoupling at the dicrotic notch
EnvRatio                Envelope ratio
C_ratio                   Compliance ratio
C_ratio_mod          Modified compliance ratio
omega1_bar          Normalized omega1 (approach-dependent)
omega2_bar          Normalized omega2 (approach-dependent)
DicroticNotch        Time location of the dicrotic notch
Duration                Duration of one cardiac cycle
Pmin                      Minimum pressure value
Pmax                     Maximum pressure value
Diast_max              Maximum pressure during diastole
Diast_time              Duration of diastole
p_notch                 Pressure at the dicrotic notch
c                            Model fitting parameter
a1                          Amplitude coefficient of omega1
b1                          Phase shift coefficient of omega1
a2                          Amplitude coefficient of omega2
b2                          Phase shift coefficient of omega2
R1                          Reflection coefficient 1
R2                          Reflection coefficient 2
HR_BPM                 Heart rate (beats per minute), calculated from cycle duration

Each of these parameters represents different aspects of cardiovascular dynamics, including intrinsic frequencies, phase angles, envelope characteristics, vascular compliance, and other waveform-derived features.

In the main dataset, all IF metrics are organized per rat across all six time points. Additional sheets contain:

- The same data reordered by metric or time point  
- Individual sheets focusing on a single metric across all time points  
- Results from various statistical analyses, which may differ depending on the metric being analyzed

The overall aim of the project is to understand how these intrinsic frequency-derived parameters vary across the occlusion and reperfusion process, potentially revealing new insights into cardiovascular behavior under stress and recovery conditions.

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Software: 
Matlab, Excel
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